Through experimentation, the U.S. Bureau of Mines has concluded that a very effective manner of avoiding explosions in mines is to cover the coal dust generated by the mining machinery with a rock dust. As is well known, coal dust in a mine is highly combustible and unless some means is provided for eliminating the explosive characteristic of the dust, explosions may occur and since the same may be ignited by sparks emenating from some of the equipment employed in the mining operation, it is compulsory that such dust be abated and rendered non-explosive. Thus, rock dust is sprayed on the ceiling, walls and floor of a mine shaft or tunnel to thereby mix with the coal dust and thereby render the coal dust substantially non-explosive in character.
With the above in mind, it is one object of the invention to provide a portable unit which may be easily transported into a mine shaft or tunnel and employed to spray a rock dust onto the ceiling, walls and floor of a mine shaft or tunnel.
Another object of the invention is to so construct a rock dust device whereby the power required for operating the dusting machine is derived from the conveyor belt commonly employed in a mine for carrying the mined coal to a suitable discharge point.
Another object of the invention is to provide a portable rock dust spraying apparatus with a means whereby the same may be easily transported to the place of use and when at that location the portable apparatus may be secured to and suspended by roof supported cables.
Another object of the invention is to provide a rock dust container with pneumatic means extending thereinto whereby the dust is prevented from caking by reasons of continuous agitation of the dust in the container.
A still further object of the invention is to provide a Venturi means at the outlet of the container for the rock dust whereby when in operation, the Venturi means will aspirate some of the rock dust from within the container at the bottom outlet and feed the same into a suitable conduit and thence sprayed onto the surfaces of the mine shaft or tunnel.
A still further object of the invention is to mount a belt engaging roller on the framework for the rock duster, one end of the roller being journalled in a suitable bearing mounted on the framework for the rock duster and the other end of the roller rotating a gear wheel which is in driving connection with a blower or fan mounted in a suitable housing.
The invention also consists in certain other features of construction and in the combination and arrangement of the several parts to be hereinafter fully described, illustrated in the accompanying drawings and specifically pointed out in the appended claims.